1. Field of the Invention
The present invention relates to a modified cereal flour and a cereal-flour processed food. The invention relates to a modified cereal flour produced by performing transglutaminase treatment during a process for producing cereal flour, such as wheat flour, from raw material cereal grains, and various cereal-flour processed foods including breads, pastas such as macaroni and spaghetti, Chinese noodles (including the wrappings of gyoza, wang-tang, and the like), Japanese noodles such as udon and soba, tempura, oil-fried quick breads such as doughnut, cakes, snacks, fresh pastries, and Japanese-style pastries.
2. Discussion of the Background
As to the modification of wheat flour for use in breads, pastries and cakes, a great deal of research has been carried out, conventionally. For example,
1. a method comprising putting wheat flour in the atmosphere of carbonate gas and ethanol at 40.degree. C. or more (Japanese Patent Publication (Kokoku) No. 6-36725);
2. a method comprising adding water at 40 to 500 % by weight into the raw material wheat, drying the resulting wheat at a temperature that does not denature, to prepare the wheat as cereal flour for pastries (Japanese Patent Publication (Kokoku) No. 5-4055); and
3. a method comprising adding an oxidant and water into wheat flour, to recover gluten with excellent processability for processed food (Japanese Patent Publication (Kokoku) No. 6-34682).
Furthermore, reports have been published about a technique to modify wheat flour by using transglutaminase (hereinafter sometimes abbreviated as "TG"), which is an enzyme catalyzing the acyl transfer reaction of the .gamma.-carboxyamide group in glutamine residues of peptides. For example, a method has been reported that comprises adding a given amount of TG to commercially available wheat flour for cakes, to prepare wheat flour with excellent taste and texture for cakes (Japanese Patent Laid-open (kokai) No. 2-286031). Also, a method involving adding TG to commercially available wheat flour to prepare dough with good elasticity for bread preparation (U.S. Pat. No. 5,279,839) has been reported.
All of the techniques described above are individually excellent from some standpoint. However, no technique which can overcome the majority of problems specific to wheat flour, as described below, has ever been reported. More specifically, the problems are:
1. deterioration, such as oxidation of wheat flour, occurs after long term storage; PA1 2. wheat flour causes allergy; PA1 3. preferable taste and texture often cannot be imparted to the final products (cereal-flour processed food) such as bread, pastries, cake, pasta and the like.